Atomic chess

In the FICS implementation, there is an added ambiguity in that while in a direct attack you're allowed to explode your opponent's king rather than defend your own if you can :P

Check was introduced to chess to "avoid the early and accidental end of a game" (wikipedia). It could easily be removed from the game... in fact, I would argue that maybe it should be removed. When one makes an illegal move in otb chess, one is usually supposed to be penalised anyway. Castling through check is the only thing that would really be affected.

So I would argue that there need be no ambiguity... just don't consider checks at all.

Having said that... I suppose there's a handful of (not fantastic) atomic-playing engines that could be affected by such a change.

@claymore I agree that not considering checks at all would be simple and unambiguous.

I think that it isn't too complex to enforce direct attacks -- with an exception for adjacent kings, since it isn't legal to capture a king when kings are adjacent. Suppose you have this position, Black to move:

White: Ka1, Qb1
Black: Ka3

In my opinion Black should be allowed to play Ka2 (or Kb2) and this endgame should be drawn. But if you interpret the FICS rules literally, due to direct attacks Black is forced to resign or play the losing Ka4??

On the other hand, in a similar position:

White: Kh1, Qb1
Black: Ka2

I have no problem with enforcing "direct attacks" and making moves other than Ka3 illegal (since on Ka1 or Kb2 kings are not adjacent and it's obvious that Black's king is en prise).

@Toadofsky: I agree that black should be able to play Ka2 and draw, I was surprised to learn that this wasn't allowed.

Is anyone coding something for bughouse?

@claymore This is why I think "direct attacks" should not apply whenever kings are adjacent. More specifically, a square adjacent to the opponent's king should not be considered "directly attacked".

This has complex implications on castling, for example:
White: Ke1, Rh1
Black: Kf2, Ra1, Nd2, Ne2

With the Black king on f2, none of the squares e1, f1, or g1 are considered "directly attacked". Therefore White may play 1. O-O!

On the other hand, I'd suggest:

White: Ke1, Rh1
Black: Ke2, Ra1

Because the g1 square is directly attacked by the Black rook, White cannot play 1. O-O.

Suddenly I'm understanding why ICC opted to ignore check altogether...